Well Screen With Drainage Assembly

ABSTRACT

A well screen assembly has an elongate base pipe having apertures therein. A filtration layer resides around the base pipe. A drainage assembly resides between the base pipe and the filtration layer. The drainage assembly includes a plurality of elongate risers carried on a mesh. The drainage layer supports the filtration layer apart from the elongate base pipe and defines an elongate passage between the base pipe and the filtration layer that communicates fluid laterally through the drainage assembly.

TECHNICAL FIELD

This description relates to filtration apparatus for use in subterranean wellbores.

BACKGROUND

For centuries, wells have been drilled to extract oil, natural gas, water, and other fluids from subterranean formations. In extracting the fluids, a production string is provided in a wellbore, both reinforcing the structural integrity of the wellbore, as well as assisting in extraction of fluids from the well. To allow fluids to flow into production string, apertures are often provided in the tubing string in the section of the string corresponding with production zones of the well. Although perforations allow for ingress of the desired fluids from the formation, these perforations can also allow unwanted materials to flow into the well from the surrounding foundations during production. Debris, such as formation sand and other particulate, can fall or be swept into the tubing together with formation fluid, contaminating the recovered fluid. Not only do sand and other particulates contaminate the recovered fluid, this particulate can cause many additional problems for the well operator. For example, as the particulate flows through production equipment, it gradually erodes the equipment. Unwanted particulate can block flow passages, accumulate in chambers, and abrade components. Repairing and replacing production equipment damaged by particulate in-flow can be exceedingly costly and time-consuming, particularly for downhole equipment sometimes located several thousand feet below the earth's surface. Consequently, to guard against particulate from entering production equipment, while at the same time preserving sufficient fluid flow pathways, various production filters and filtration methods have been developed and employed including gravel packs and well screen assemblies.

A number of well screen filtration designs have been employed. A well screen assembly is a screen of one or more layers installed in the well, capable of filtering against passage of particulate of a specified size and larger, such as sand, rock fragments and gravel from surrounding gravel packing. The specific design of the well screen can take into account the type of subterranean formation likely to be encountered, as well as the well-type.

SUMMARY

An aspect encompasses well screen assembly with an elongate base pipe having apertures therein. A filtration layer resides around the base pipe. A drainage assembly resides between the base pipe and the filtration layer. The drainage assembly includes a plurality of elongate risers carried on a mesh. The drainage layer supports the filtration layer apart from the elongate base pipe and defines an elongate passage between the base pipe and the filtration layer that communicates fluid laterally through the drainage assembly.

An aspect encompasses a screen assembly for use in a well. The screen assembly includes an elongate apertured tubing and a first mesh layer carried on the tubing. The screen assembly further includes a second mesh layer between the first mesh layer and the apertured tubing and a third, non-woven mesh layer between the second mesh layer and the apertured tubing. The third, non-woven mesh layer is formed from a planar non-woven mesh sheet wrapped into a cylindrical shape. The planar sheet has a first plurality of wires oriented in generally the same direction and residing in a first plane and a second plurality of wires affixed to the first plurality of wires and residing in a second plane.

An aspect encompasses a method of communicating fluids in a well. In the method particulate is filtered from a fluid with a filtration layer of a well screen assembly. The fluid is communicated laterally through the well screen assembly via an elongate passage defined in a drainage assembly of the well screen assembly. The drainage assembly resides between the filtration layer and a base pipe of the well screen assembly and includes a plurality of elongate risers carried on a mesh that support the filtration layer apart from the elongate base pipe and define the elongate passage.

One or more of the aspects can include some, none or all of the following features. The plurality of risers can be wires of a second mesh carried by the first mentioned mesh. The second mesh can be a non-woven mesh. The plurality of risers can be risers that are not arranged in a mesh. The risers can be oriented substantially longitudinally with respect to the elongate base pipe and the elongate passage call extend substantially the entire length of the drainage assembly unobstructed by structures transversely crossing the passage. The risers can define a plurality of elongate passages and the of passages can be substantially parallel to one another. The filtration layer can be a wire mesh and the risers can be of a lower gage than the wires of the filtration layer wire mesh. The filtration layer can be a wire mesh and a greatest dimension between wires of the filtration layer wire mesh can be smaller than a greatest dimension between risers of the drainage assembly. The filtration layer can be a wire mesh and a greatest dimension between wires of the filtration layer wire mesh can be smaller than a greatest dimension between wires of the drainage assembly mesh. The well screen assembly can include an apertured shroud pipe around the filtration layer.

DESCRIPTION OF DRAWINGS

FIG. 1A is a side cross-sectional view of an example well system including a plurality of well screen assemblies.

FIG. 1B is a side cross-sectional view of an example well screen assembly.

FIG. 2A is a perspective view of an example drainage assembly.

FIG. 2B is an axial cross-sectional view taken intermediate the ends of an example well screen assembly incorporating the drainage assembly of FIG. 2A.

FIG. 2C is a perspective view of an example drainage assembly incorporating a welded wire mesh.

FIG. 2D is an axial cross-sectional view taken intermediate the ends of an example well screen assembly incorporating the drainage assembly of FIG. 2C.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIG. 1 illustrates an example well system 10 including a plurality of well screen assemblies 12. The well system 10 is shown as being a horizontal well, having a wellbore 14 that deviates to horizontal or substantially horizontal in the subterranean zone of interest 24. A casing 16 is cemented in the vertical portion of the wellbore and coupled to a wellhead 18 at the surface 20. The remainder of the wellbore 14 is completed open hole (i.e., without casing). A production string 22 extends from wellhead 18, through the wellbore 14 and into the subterranean zone of interest 24. A production packer 26 seals the annulus between the production string 22 and the casing 16. The production string 22 operates in producing fluids (e.g., oil, gas, and/or other fluids) from the subterranean zone 24 to the surface 20. The production string 22 includes one or more well screen assemblies 12 (two shown). In some instances, the annulus between the production string 22 and the open hole portion of the wellbore 14 may be packed with gravel and/or sand (hereinafter referred to as gravel packing 26 for convenience). The well screen assemblies 12 and gravel packing 26 allow communication of fluids between the production string 22 and subterranean zone 24. The gravel packing 26 provides a first stage of filtration against passage of particulate and larger fragments of the formation to the production string 22. The well screen assemblies provide a second stage of filtration, and are configured to filter against passage of particulate of a specified size and larger into the production string 22.

Although shown in the context of a horizontal well system 10, well screen assemblies 12 can be provided in other well configurations, including vertical well systems having a vertical or substantial vertical wellbore, multi-lateral well systems having multiple wellbores deviating from a common wellbore and/or other well systems. Also, although described in a production context, well screen assemblies 12 can be used in other contexts, including injection, well treatment and/or other applications.

As shown in FIG. 1A example well screen assembly 12 includes an apertured base pipe 100 (with square, round, slotted and/or other shaped apertures 140) that carries well screen layers 105 including a drainage assembly 110. The drainage assembly 110 includes a standoff layer 120 adjacent, and in some instances bonded to (e.g. welded, brazed and/or adhered) and carried by, a support layer 115. In some implementations, the standoff layer 120 can be disposed between the support layer 115 and the base pipe 100 (as shown), between the support layer 115 and other layers 105 exterior the drainage assembly 110, or a standoff layer 120 can be disposed both between the support layer 115 and the base pipe 100 and between the support layer 115 and other Layers 105 surrounding the drainage assembly 110. The drainage assembly 110 is configured to facilitate passage of fluids laterally through the well screen assembly 12, and in certain instances, facilitate passage of fluid axially along the length of the well screen assembly 12. For example, standoff layer 120 creates a standoff between the base pipe 100 and other layers 105, thereby forming elongate passageways 122 through which flow of fluid is communicated. In some implementations, the passageways 122 can be continuous and unobstructed for the length (the entire or substantially entire length) of the drainage assembly 110 or for only a portion of the length of the drainage assembly 110 (e.g., approximately ¾, ½, ¼, ⅛, 1/16, 1/32 the length or other portion of the length of the drainage assembly). Support layer 115 supports other layers 105 exterior to the support layer 115 from collapsing into, and thus obstructing or partially obstructing, the passageways 122 created by the standoff layer 110. Communication of fluids through the standoff layer 120 can facilitate more uniform distribution of flow to the apertures 140 intermediate the ends of the base pipe 100, thus improving fluid flow between the interior and exterior of the well screen assembly 12. Communication of fluids through the standoff layer 120 can facilitate passage of fluids to the ends of the well screen assembly 12. For example, communicating fluids to the ends of the well screen assembly 12 may be desirable in instances where flow is communicated between the well screen layers 105 and the interior of the base pipe 100 at the ends of the well screen assembly 12 via a screen valve, inflow control device, and/or otherwise.

Well screen layers 105 further include a filtration layer 125 that operates as the primary fine filtering mechanism of the well screen assembly 12, and is configured to allow flow of fluid and filter against passage of the smallest particulate filtered by the well screen assembly 12. The filtration layer 125 can have the highest mesh per inch count and/or the smallest apertures therethrough of ally the other well screen layers 105. Although only one filtration layer 125 is shown, in some instances, additional filtration layers can be included and/or the filtration layer can be incorporated into the drainage assembly 110 (such as support layer 115). If multiple filtration layers 125 are provided, they can each be configured to filter against passage of the same size particulate or one or more of the filtration layers 125 can be configured to filter against passage of different size particulate.

Well screen assembly 12 includes an outer shroud 130 surrounding the well screen layers 105 and forming the exterior of the well screen assembly 12 to protect and preserve the integrity of the layers beneath. In certain instances, the outer shroud layer 130 is an apertured pipe having square, circular, slotted and/or other shaped apertures 135 that allow passage fluid through the outer shroud layer 130. The outer shroud 130 may perform an initial filtering function, filtering against passage of larger particulate into the well screen layers 105 beneath.

Although only a drainage assembly 110 and filtration layer 125 have been discussed above, the well screen assembly 12 can include additional layers of additional types and/or additional drainage assemblies 110 and/or filtration layers 125 can be included beneath the outer shroud 130.

FIG. 2A illustrates a perspective view of an example drainage assembly 200 having a standoff layer 210 that resides within a support layer 225. The standoff layer 210 includes a plurality of longitudinal (i.e., parallel or substantially parallel to the longitudinal axis of the drainage assembly, and thus well screen assembly) oriented, elongate risers 205 bonded to all interior surface 220 of a support layer 225. The longitudinally oriented risers 205 form elongate longitudinal passageways 215 therebetween that facilitate passage of fluid longitudinally along the drainage assembly 200. The longitudinal passageways, as shown, are continuous for the length (the entire length or substantially the entire length) of the drainage assembly 200, and wholly unobstructed by transverse crossing wires or other transverse structures. Although shown as round wire or rods, risers 205 can may have cross-sectional profiles exhibiting a variety of different geometries. For example, risers 205 can have rectangular, triangular, or other-shaped cross-sections. Also, risers 205 can be continuous members, or non-continuous members, such as raised nodules formed into and/or bonded to the surface of the support layer 225. Although shown as longitudinal passageways 215, the risers 205 can be arranged to define passageways 215 in other directions (e.g., circumferential, helical, and/or other).

In some implementations, see for example FIG. 2C, a welded mesh (e.g., a square welded mesh, and/or other mesh) can be used in lieu of or in addition to the plurality of individual risers 205. A welded mesh is a non-woven mesh that includes a first plurality of parallel wires 250 oriented in one direction with a second plurality of parallel wires 255 welded, brazed and/or otherwise affixed to the first plurality of wires, and oriented in a second direction. In a square welded mesh, the first and second directions are substantially perpendicular and the spacing between crossing wires is substantially equal to define square spaces between the wires. Typically all of the first plurality of wires 250 reside on one side of the mesh and all of the second plurality of wires 255 reside on the opposite side of the mesh. Welded mesh is typically pre-manufactured and commercially available formed in a flat sheet, and could be rolled into a tubular shape for use as standoff layer 210. For example, when the mesh is flat, the first plurality of wires 250 reside entirely in one plane and the second plurality of wires 255 reside entirely in a different plane. In some implementations, the welded mesh may be positioned in the drainage assembly 200 with the wires on the inner surface of the standoff layer 210 oriented longitudinally along the drainage assembly 200 (i.e., defining risers) and wires on the outer surface of the standoff layer 210, adjacent the support layer 225, circumferentially around the drainage assembly 200. As such, the longitudinally oriented wires of the wire mesh define risers 205 and the longitudinal passageways between. The circumferentially oriented wires, being on the outside of the mesh, do not obstruct the longitudinal passageways. In some implementations, the gage of the wires on the inner surface of the standoff layer 210 can be smaller (i.e., larger diameter) than the gage of the wires on the outer surface of the standoff Layer 210. In some instances, the spacing between adjacent wires on the inner surface of wire mesh standoff layer 210 can be greater than the spacing between adjacent wires on the outer surface of the wire mesh standoff layer 210.

Support layer 225 can be a welded and/or woven mesh (e.g., a square welded mesh, a square woven mesh, and/or other mesh). In certain instances, the mesh per inch count of the support layer 225 is higher (i.e., able to filter against passage of a smaller particulate) than the mesh per inch count of the standoff layer 210. In certain instances, the wire gage of the support layer 225 is higher (i.e., smaller diameter) than the wire gage of some or all of the wires in the standoff layer 210. In certain instances, the wire gage of warp wires in the standoff layer 210 are larger than the warp and/or weft layers of the support layer 225. Of note, the use of the term “mesh” herein is used to exclude wrapped wire screen, i.e. a screen formed in a cylinder by helically wrapping wire about a plurality of longitudinal wires arranged in a generally cylindrical shape.

FIG. 2B is an axial cross-sectional view taken intermediate the ends of an example well screen assembly 240 incorporating drainage assembly 200 carried on a base pipe 230. FIG. 2B also shows the inclusion of a mesh filtration layer 235 and protective, outer shroud layer 245 in the well screen assembly 240. As is shown, risers 205 contact the outer surface of base pipe 230, supporting and separating the support layer 225 from the base pipe 230. Risers 205 can be bonded (e.g., welded, brazed, adhered and/or otherwise bonded) to the support layer 225 prior to wrapping the support layer 225 (and risers 205) around the base pipe. In other examples, risers 205 can be bonded to, and positioned around the exterior surface of base pipe 230 prior to the support layer 225 being wrapped around the base pipe 230. The skeleton of risers 205 surrounding the base pipe 230 provide an offset h between the base pipe 230 and support layer 225. Both the offset h and the width w between risers 205 is greater than the height or width of any other passage in the filtration layer 235. Indeed, in other implementations, the base pipe 230 can be manufactured so as to form the rib members 205 or other standoff risers, into the structure of the base pipe 230 itself.

FIG. 2D is an axial cross-sectional view taken intermediate the ends of an example well screen assembly 240′ incorporating welded wire mesh drainage assembly 200′. The well screen assembly 240′ has a similar construction to well screen assembly 240, except that the drainage assembly 200′ incorporates a welded wire mesh as standoff layer 210′.

A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. 

1. A well screen assembly, comprising: an elongate base pipe having apertures therein; a filtration layer around the base pipe; and a drainage assembly between the base pipe and the filtration layer, the drainage assembly comprising a plurality of elongate risers carried on a mesh, the drainage layer supporting the filtration layer apart from the elongate base pipe and defining an elongate passage between the base pipe and the filtration layer that communicates fluid laterally through the drainage assembly.
 2. The well screen assembly of claim 1, wherein the plurality of risers comprise wires of a second mesh carried by the first mentioned mesh.
 3. The well screen assembly of claim 2, wherein the second mesh is a non-woven mesh.
 4. The well screen assembly of claim 1, wherein the plurality of risers are not arranged in a mesh.
 5. The well screen assembly of claim 1, wherein the risers are oriented substantially longitudinally with respect to the elongate base pipe and the elongate passage extends substantially the entire length of the drainage assembly unobstructed by structures transversely crossing the passage.
 6. The well screen assembly of claim 1, wherein the risers define a plurality of elongate passages and the of passages are substantially parallel to one another.
 7. The well screen assembly of claim 1, wherein the filtration layer is a wire mesh and the risers are of a lower gage than the wires of the filtration layer wire mesh.
 8. The well screen assembly of claim 1, wherein the filtration layer is a wire mesh and a greatest dimension between wires of the filtration layer wire mesh is smaller than a greatest dimension between risers of the drainage assembly.
 9. The well screen assembly of claim 8, wherein the filtration layer is a wire mesh and a greatest dimension between wires of the filtration layer wire mesh is smaller than a greatest dimension between wires of the drainage assembly mesh.
 10. The well screen assembly of claim 1, further comprising an apertured shroud pipe around the filtration layer.
 11. A screen assembly for use in a well, comprising: an elongate apertured tubing; a first mesh layer carried on the tubing; a second mesh layer between the first mesh layer and the apertured tubing; and a third, non-woven mesh layer between the second mesh layer and the apertured tubing, the third, non-woven mesh layer formed from a planar non-woven mesh sheet wrapped into a cylindrical shape, the planar sheet having a first plurality of wires oriented in generally the same direction and residing in a first plane and a second plurality of wires affixed to the first plurality of wires and residing in a second plane.
 12. The screen assembly of claim 11, wherein the third, non-woven mesh layer comprises a square mesh.
 13. The screen assembly of claim 11, wherein the first plurality of wires are oriented substantially longitudinally along the elongate apertured tubing and define an elongate passage that extends substantially the entire longitudinal dimension of the third, non-woven mesh layer unobstructed by structures transversely crossing the passage.
 14. The screen assembly of claim 11, wherein first mesh layer is a wire mesh and the first plurality of wires of the third, non-woven mesh are of a lower gage than the wires of the first mesh layer.
 15. The screen assembly of claim 11, wherein the first mesh layer is a wire mesh and a greatest dimension between wires of the first mesh layer is smaller than a greatest dimension between the first plurality of wires of the third, non-woven mesh.
 16. The screen assembly of claim 11, wherein the third, non-woven mesh is affixed to the second mesh.
 17. A method of communicating fluids in a well, comprising: filtering particulate from a fluid with a filtration layer of a well screen assembly; and communicating the fluid laterally through the well screen assembly via an elongate passage defined in a drainage assembly of the well screen assembly, the drainage assembly residing between the filtration layer and a base pipe of the well screen assembly and comprising a plurality of elongate risers carried on a mesh that support the filtration layer apart from the elongate base pipe and define the elongate passage.
 18. The method of claim 17, wherein the plurality of risers comprise wires of a second, non-woven mesh carried by the first mentioned mesh.
 19. The method of claim 17, wherein the plurality of risers are not arranged in a mesh.
 20. The method of claim 17, wherein the risers are oriented substantially longitudinally with respect to the elongate base pipe and the elongate passage extends substantially the entire length of the drainage assembly unobstructed by structures transversely crossing the passage. 